Column chromatography of all types continues to be a standard method of operation in the laboratory and the commercial marketplace for the separation of materials. The estimated market of $250-300 million for chromatography consumables, out of the billion dollar market for products for separation processes, by the year 1990, represents a 15-20% growth factor for this type of product. Although a wide variety of technologies continue to take advantage of the separation capabilities offered by modern column chromatography, one technology particularly driving the expansion of the column chromatography consumables market is generally referred to as biotechnology. In particular, the separation and purification of biologically produced materials resulting from genetic engineering technology is placing significant demands on the ability of the marketplace to meet the need to provide chromatography columns which are capable of high loadings, and rapid and reproducible results, at a reasonable price.
At the same time, the demands of technology are increasingly requiring higher precision and accuracy in the separation of exceedingly fine dimension, calling for chromatography beds which are capable of separating, in use, nearly identical fractions. Because of the nature of the product, and the increased requirements for safety, particularly in areas where human consumption is involved, it is absolutely essential that these separations be constant and reproducible, from batch to batch, laboratory to laboratory, and between commercial establishments.
One of the most commonly employed methods for creating a liquid chromatographic bed involves introducing the chromatographic material, which may be, e.g., a silica gel, into a column in the presence of a suspending liquid, with the outlet end of the column blocked, and thereafter applying a high pressure pump to the open end and removing the fitting at the outlet and, thereby draining a large volume of liquid through the bed, to pack it down.
This process, which may generally be referred to as dynamic packing, in which the liquid is pressurized and forced to flow through the bed, has significant disadvantages. In particular, flowing the liquid through the bed under pressure to achieves column compaction and frequently causes "channeling" or preferential flow characteristics, caused by the resistive flow of pressurized liquid through the bed. The application of high pressure packing techniques are labor intensive and too costly to be used to prepare disposable chromatographic columns. Otherwise, the materials employed therein are relatively inexpensive. In other instances, the use of high pressure pumps can cause laboratory damage and injury, particularly when end fittings on the column blow off under the application of pressure, the released fitting can fly off at high velocity.
Accordingly, it remains a clear need of the art to provide a method for bed packing of chromatography columns which is not labor intensive, produces accurate and reproducible results and does not expose the worker or the laboratory to the risk of injury or damage.